1. Field of the Invention
This invention relates to an image holding member to hold thereon an electrostatic image and/or a toner image.
2. Description of the Prior Art
For the image holding member, on which the toner image and electrostatic image are formed, there exists electrophotographic photosensitive members and other image holding members.
The electrophotographic photosensitive member can take various embodiments for obtaining predetermined characteristics, depending upon the kinds of the electrophotographic process to be adopted. As a representative electrophotographic photosensitive member, there is one which has a photoconductive layer formed on a base member (or a substrate), and another one that has an insulative layer provided on its surface. These electrophotographic photosensitive members are widely used. The photosensitive member constructed with the substrate and the photoconductive layer is used in the image formation by the most general electrophotographic process, i.e., the image formation by electric charging, image exposure, image development, and, further, image transfer, if necessary. In the photosensitive member having the insulating layer, this insulating layer is for various purposes; for example, protection of the photoconductive layer, improvement in the mechanical strength of the photosensitive member, improvement in the dark decay characteristic, adaptation of the photosensitive member to a particular electrophotographic process (pollution prevention), and various others. Representative examples of the electrophotographic process using the photosensitive member having such insulating layer are: U.S. Pat. No. 2,860,048, Japanese Patent Publication No. 41-16429, Japanese Patent Publication No. 38-15446 (corresponding to U.S. Pat. No. 3,146,145), Japanese Patent Publication No. 46-3713 (corresponding to U.S. Pat. No. 3,607,258), Japanese Patent Publication No. 42-23910 (corresponding to U.S. Pat. No. 3,666,363), Japanese Patent Publication No. 43-24748 (corresponding to U.S. Pat. No. 3,734,609), Japanese Patent Publication No. 42-19747 (corresponding to U.S. Pat. No. 3,457,070), Japanese Patent Publication No. 36-4121 (corresponding to U.S. Pat. No. 3,124,456), and others.
The electrophotographic photosensitive member is utilized in a predetermined electrophotographic process, during which an electrostatic image is formed, and this electrostatic image is developed to be visualized.
In the following, a few representative examples of the process, in which other image holding members are used, will be explained.
(1) A process such as disclosed in Japanese Patent Publication No. 32-7115, Japanese Patent Publication No. 32-8204, and Japanese Patent Publication No. 43-1559, wherein, with a view to improving the repetitive use of the electrophotosensitive member, an electrostatic image formed on it is transferred to another image holding member for development, and then the toner image is further transferred onto a recording member.
(2) A process for forming an electrostatic image on another image holding member in correspondence with the electrostatic image formed on the electrophotosensitive member, such as disclosed in Japanese Patent Publication No. 45-30320 (corresponding to U.S. Pat. No. 3,680,954), Japanese Patent Publication No. 48-5063 (corresponding to U.S. Pat. No. 3,645,614), Laid-Open Japanese Patent Application No. 51-341 (corresponding to U.S. Ser. No. 771,309 filed Feb. 23, 1977), and others, wherein an electrostatic image is formed by a predetermined electrophotographic process onto a screen-shaped electrophotosensitive member having a multitude of tiny openings; then a corona charging treatment is effected on another image holding member through this electrostatic image, thereby modulating the corona ion current to form the electrostatic image on the other image holding member; thereafter the electrostatic image is developed with toner, and this toner image is transferred onto a recording member to be the final reproduction image.
(3) A process by another electrostatic image forming process, according to which an electrical signal is applied to (multi-)needle electrode(s) to form an electrostatic image on the surface of the image holding member in accordance with the electrical signal.
The image holding members to be used for the electrophotographic process as stated in the above items (1) to (3) may only be insulative in their electrostatic holding surface, and need not have a photoconductive layer.
Thus, the member to hold thereon an electrostatic image or a toner image, which is an electrophotographic photosensitive member or a member having no photoconductive layer, as the image holding member, is required to have its electrical characteristics in accordance with the electrophotographic process to be adopted. In addition, durability and cleaning property also constitute important factors in the image holding member. In more detail, durability is required when the image holding member is repetitively used, while the cleaning property relates to the facility of removing the residual toner which has adhered to the surface of the image holding member. Both properties of which considerably affect the clear image formation and, further, prevention of the cleaning device from damage. On account of this, an insulating layer having excellent durability and cleaning property is desired for improving the durability and cleaning property of the image holding member.